The 100 trillion microbes that live in your gut know—and influence—you from the inside out. So what can they tell you about yourself? Here's a taste...

By Jena Pincott

Photo: Thinkstock

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"You're Taking the Wrong Chill Pill"

Try this to preempt stress-triggered pig-outs: two 1/4-cup servings daily of yogurt that is (preferably) unsweetened and (crucially) probiotic-enriched (look for B. animalis, S. thermophilus and L. bulgaricus). After a month of this regime, volunteers in an fMRI study at UCLA's School of Medicine showed brain activity that's associated with greater emotional stability (a stronger connection between pain-processing circuits and the prefrontal cortex), compared with the non-probiotic control group. One explanation: The good bacteria in yogurt send out signals that increase serotonin, the neurotransmitter that famously reduces anxiety. While most probiotic eaters don't have big mood changes, says lead author Kirsten Tillisch, MD, many (anecdotally) say they feel calmer over time. Ongoing research focuses on the subtle, cumulative, long-term effects of microbes as anxiety reducers.